Composite modular self actuating variable pitch marine propeller

ABSTRACT

This invention provides a composite modular self-actuating, variable pitch propeller with a cylindrical hub housing assembly, a plurality of blades that automatically adjust between an initial, fixed low pitch setting and multiple higher pitch settings that occur in response to centrifugal force, water pressure, spring tension and height adjustment of the upper section of the device and cam profile of the inner section of the blades and adjacent cam ramp on the hub. Also provided is an over hub exhaust design that allows engine exhaust to exit thru ports in the exterior wall of the hub section. Additionally, a threaded cap and spring in the top section provides a means of adjustment to limit the maximum high pitch. Finally, each blade includes a protruding cam profile perpendicular to the blade shaft axis, with a flat surface acting as a low pitch stop and a profile that extends upward.

This invention relates to automatic, variable pitch plastic propellers wherein the blade pitch automatically adjusts between a wide range of pitch positions.

BACKGROUND OF THE INVENTION

Unlike automobiles that have multiple gears allowing for a smooth transition between stopped and high speed and providing a means of reducing the stresses induced in the drive train upon acceleration. boats are limited to a one speed gear case. The only available variable allowing for reduced stresses and better top speed or acceleration is the pitch of the propeller. For a pleasure boat requiring best top speed, one would need to use a high pitch propeller of say a 23 pitch. If one was in need of pulling heavy loads, then a low pitch propeller is needed of say a 17 pitch. The problem has always been that you cannot have the best of both worlds for any given situation.

There have been a variety of modern day improvements on the requirement of a single pitch on a propeller. Several devices have been designed that utilize a propeller with changeable pitch settings within one propeller, but require the user to stop the boat in order to make any changes with tools, to the propeller. A few examples are in U.S. Pat. Nos. 4,930,987 which I will come back to later, 3,790,304, 3,216,507.

The prior art of propellers that vary pitch settings during normal engine operation, without the need to stop for adjustments have taken basically two forms. First are the ones that automatically change pitch settings based on operating conditions such as RPM and water pressure. the second type requires an operator interface control utilizing such means as hydraulic or pneumatic.

Three of the latest propellers are of most interest to my invention. They are patents of U.S. Pat. Nos. 5,549,455, 4,929,153, 5,032,057. These patents incorporate the use of complex linkages and weights to accomplish the change in blade pitch. They are in use today, but are exclusive in price such that the average pleasure boater cannot afford one. The second is by Land and Sea in the 1980's which is U.S. Pat. Nos. 5,061,212 and 5,851,131. They utilized spring tension on blades, with a complex array of pins and adjusting screws, with a spring for each blade. These were hard to adjust or keep adjusted and expensive for the day again.

Fast forwarding in time reveals that plastic manufacturing techniques have advanced to the point of being useful as a replacement for aluminum for propellers as evidenced by U.S. Pat. No. 4,483,214 showing use of carbon and glass fibers in epoxy resins for a high speed flywheel. Further evidence of the use of these modern plastics is in U.S. Pat. No. 4,930,987 by Piranha, using these plastics in a modular, fixed pitch propeller.

The prior art does not include a practical, cost efficient variable pitch marine propeller like the present invention.

SUMMARY OF THE INVENTION

The marine propeller assembly of the present invention is the only practical, simple, durable and cost effective alternative to the available variable pitch marine propellers of today. the propeller of the present invention can be manufactured for a fraction of the cost of any competitor of today and is competitive even of some of today's fixed pitch propellers for cost. The present invention is interchangeable for use in a wide variety of boat motors.

Accorded with the present invention, the hub housing, cap and blades are multiple separate parts, comprising a lower, middle and upper section of the hub housing, along with an upper end cap, one compression spring, an off the shelf splined insert for boat motor alignment and multiple blades that all assemble together.

The blades, whose shafts incorporate the low pitch stop and cam pitch change enabling extrusion, are easily replaceable in the event of any of them being damaged, without the need to replace the entire propeller assembly.

The present invention utilizes side exit ports in the bottom section, incorporating a funnel venturi over hub exhaust exit system, exiting exhaust just in front of the blades, that improves top speed, while, due to the low initial pitch setting of the blades, does not suffer from any acceleration losses.

In the preferred embodiment, each blade has its root section retained within the hub sections by a larger diameter shoulder on each blade shaft that is interlocked within the same diameter shoulder pocket areas within the hub sections, thus these pocket areas in the hub housings retain each blade securely and allow for easy assembly and disassembly when needed. Each blade also contains a transverse section protruding from the root shaft area that provides a flat surface used for a rotational stop position of the blade shaft and a cam profile adjoining same transverse section for transferring rotational movement of the blade shaft to the upper sections of the hub housing for pitch change control. The blade shaft is also not centered on the blade surface but is biased toward the posterior end of the blade for better up pitch control. the blades are also free to move outward from the center hub axis and rotate on their shafts, said rotation controlled by water pressure and a ramp on the flat hub bottom section, adjacent to the cam profile, so centrifugal force and water pressure force are allowed to act independently on the blades.

The present invention includes passages formed within the middle hub section to allow contact from the previously named blade cam profile to the upper hub section, thus transferring and converting rotational movement of the blade shaft to linear, vertical movement of the upper section. The middle hub section also contains a threaded area for an end cap and a hollow section within that threaded area to house an off the shelf splined insert used to join the propeller to a standard boat motor splined shaft.

Present invention further includes an upper hub section whose flat bottom is used to contact the previously referred to blade cam area. This upper section includes a pocket to house a compression spring used to provide tension between the flat bottom and the blade cam area.

This invention further includes a threaded upper end cap that threads onto the threaded area of the previously referred to middle hub section. This cap also contains a hollow area to house the upper portion of the previously referred to compression spring. When turned, this cap provides a limit to the vertical travel of the upper hub housing when the blade cam area rotates, and provides a controlled amount of spring tension between the blade cam area and the top hub flat bottom surface.

The novel features that are characteristic of the present invention, both in type of operation and its organization, along with additional objects and advantages therein, can be better understood after reviewing the following descriptions connected with the drawings accompanying, where the preferred embodiment of the invention is thoroughly illustrated by way of multiple examples. It needs to be expressly understood that the drawings illustrated are for purpose of description only and are not intended to define the limits of the invention or extrapolations that would be apparent to one skilled in the art and area of this device.

DESCRIPTION OF THE DRAWINGS

In the preferred embodiment of this invention, all of the parts are injection molded parts made from a type of plastic known as VERTON which contains 30 percent of long fiber filler. Main components are listed on sheet 1.

FIG. 1 is an exploded three dimensional view of the propeller assembly according to the preferred embodiment of this invention.

FIG. 2 is a front plan view of the propeller of FIG. 1 and,

FIG. 3 is an isometric view of the blade of FIGS. 1 and 2

FIG. 4 is an isometric view of the hub bottom section from bottom

FIG. 5 is an isometric view of the hub bottom section from top

FIG. 6 is an isometric view of the hub middle section from bottom

FIG. 7 is an isometric view of the hub middle section from top

FIG. 8 is a plan sectional view of the hub top section

FIG. 9 is a plan sectional view of the top end cap

FIG. 10 is an isometric view of the hub bottom section with blade attached

FIG. 11 is an isometric view of the hub middle section with blade attached

FIG. 12 is a plan sectional view of the propeller assembly

FIG. 13 is a detail, plan sectional view of the upper section of the propeller

FIG. 14 is a detail, plan sectional view of the top section of the propeller FIG. 15 is an isometric view of the bottom hub section with blades

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Now referring to the drawings, FIGS. 1-14, they show the propeller assembly of the present invention, which typically has bottom, middle and top hub sections that are coupled together, along with a top cap, a compression spring and four blades. The diameter of the entire propeller is typically 16 inches and is intended for engines with horsepower up to 300 horsepower and all parts with the exception of the spring, nuts and splined insert are made of a plastic known as VERTON, containing 30 percent long fiber filler.

With reference to FIG. 1, and by way of a brief overview, the propeller assembly includes a bottom hub section A, 4 unitary blade and root portions B, a middle hub section C, a top hub section D, a compression spring E and a top end cap F.

By way of assembly and in reference to FIG. 1, the four blades B, which are shown in FIG. 3, are represented by a main blade area, a blade shaft 2, large blade shaft end 3, a flat section of a transverse protrusion 4, a cam profile section of the same transverse protrusion 5, an anterior end of the blade section 6 and a posterior end of the blade section 7.

FIG. 2, points out a circular area of the hub section A, that when blades B rotate on their shafts, prevents interference with the anterior 6 and posterior 7 ends of the blade.

FIG. 4 shows boat motor shaft attachment cavity 8 and 12 of hub section A, where propeller attaches to boat motor. Motor exhaust gases enter cavity 9 and are funneled down 4 coned shaped cavities and passages 10, increasing air volume creating a venturi effect for better exhaust gas pressure. Exhaust gases then exit the hub section A through 4 side ports 11.

FIG. 5 further shows hub section A illustrating studs 13 which protrude through hub section C for attachment of lower and middle hub sections. Further shown in this figure are splines 14 for capturing off the shelf splined insert used to align propeller to boat motor shaft. Additionally, pockets 15 are the mating surfaces for blade shafts 2 and 3. Ramp 16 for blade flat 5 is shown as well as flat surface 17 which is the contact surface for blade shaft flat surfaces 4 on initial setup and start position.

FIG. 6 shows the middle hub section C, illustrating mating stud holes 18 for studs 13, cam slot openings 18 which are clearance for cam protrusions 5. Further illustrated are pockets 19 and large pockets 20, which are the mating halves of pockets 15 and 16 for capturing blade shafts and ends 2 and 3.

FIG. 7 shows the middle hub section C from upper view showing threaded area 21 which is the attachment threads for upper end cap F. Further illustrated are the hollow opening 22 for access to splined shelf 23 which is where the off the shelf splined insert sits. Also shown are the splines 24. This view also shows the sliding surfaces of 25 which aligns to sliding surfaces of top hub section D, shown in additional view.

FIG. 8 which is a side sectional view of hub top section D shows the flat cam contact surface 27 which contacts blade cam profile protrusion 5. Also shown are the sliding surfaces 28 which slide up and down on connected sliding surfaces 25 of hub middle section C, spring pocket 29 which houses the spring E, and cap surface 30 which spaces off the spring from top end cap F surface 32.

FIG. 9 which is a side sectional view of top end cap F, shows threads 31 which thread onto threads 21 of hub middle section C, spring pocket 32 which houses the other end of spring E and contact surface 33 which spaces off the spring from hub top section D.

FIG. 10 which is an isometric view of hub bottom section A with blades B sitting in pockets 15, 2 and 3. Also shown is the contact of flat surface 17 in contact with blade flat contact surface 4 in the initial low pitch starting biased position before blade shaft rotates upon sufficient pressure to move off of flat surface position. Also shown is cam ramp 16 and interface of ramp 16 and 4 represented by notation 34.

FIG. 11 which is an isometric view of hub middle section C with blades sitting in pockets 20,2,21 and 3. This view further shows the cam opening interfaces of openings 19 in hub middle section C and blade cam surfaces 5.

FIG. 12 which is a side sectional view of the entire propeller shows all interfaces of adjoining parts named above in clearer detail as an assembled unit. Clearly shown are the interfaces of assembled pockets 19, 20, 15, 2 and 3 showing how the blade shafts nest into the hub assembled bottom and middle sections.

FIG. 13 which is a close up of FIG. 12, shows the assembled interfaces of the blade shaft cam surface 5 thru hub middle section slots 18 and the flat blade surface of the blades 4 mating with the flat surface of the hub bottom section 17. Also shown is the interface of the blade shaft cam surface 5 with the flat surface of the hub top section 27.

FIG. 14 which is another close up of FIG. 12 further up, showing the assembled interfaces of the spring E and the hub top section pocket 28. In addition, the spring interface with the top end cap F surface 33.

FIG. 15 is an isometric view of the bottom hub section with blades, showing 35 which represents the blade shaft moved outward from the hub center, contacting ramp 15 with blade surface 4. 36 shows the blade moved inward from the hub center. 37 shows the interface of ramp 16 and blade flat 4.

By way of explaining the assembly sequence related to the individual modular parts of FIGS. 1-14, I would add the following procedure. The blade shafts are positioned into the pockets of the hub lower section with the flat protruding surfaces against the flat top surface of the hub bottom section. Then the hub middle section has an off the shelf splined insert described earlier positioned into the splines and seated on the flat shelf described earlier. This hub middle section is then positioned onto the hub bottom section aligning the stud holes over the studs in hub bottom section. This seats the two hub sections together capturing the blade shafts. Four ¼-28 locknuts are then tightened over the hub bottom studs protruding through the stud holes in hub middles section. This sub assembly is then positioned over the boat motor shaft and seated against the boat motor shaft. A supplied ¾ inch locknut is then threaded onto the protruding boat motor threaded shaft that protrudes through the splined insert and tightened. The hub top section is then positioned onto the hub middle section until the bottom surface of the hub top section contacts the blade cam surfaces. The spring is then inserted into the hub top section seating on the hub top section spring pocket. Finally, the top end cap is positioned over the spring aligning the spring to the top end cap spring pocket and then threaded onto the protruding threads of the hub middle section. This cap is threaded until the desired gap is achieved between the top end cap flat surface and the hub top section clearance flat surface described earlier. You now have a complete adjusted propeller onto a boat motor shaft. This assembly and setup adjustment process takes less than a minute.

Thus, there has been described a modular, variable pitch marine propeller assembly that serves as the only low cost, simple and robust alternative to the high cost complex alternative variable pitch marine propellers available today and is competitively priced to available standard fixed pitch propellers available today. The individual blades can be easily replaced if damaged without having to replace the entire propeller assembly. The foregoing detailed description of this invention in its desired embodiment is not considered to be the only embodiment as other versions of this invention would be obvious to one skilled in the art and would fall within the scope of this invention. 

We claim:
 1. A variable pitch marine propeller, made of ultra high strength durable plastic, comprising a modular hub housing of multiple sections, that is cylindrical in shape, with a circular opposing exterior shape encapsulating a plurality of blades thru multiple pockets in said housing, said blades extending outward radially from the housing pockets, with each blade rotating with and in the same direction as the housing, while being constrained within the housing to prevent ejection, while allowing for axial movement away from the center of the hub and pivotal rotation of the blades axially within the pockets, such rotation being caused by increasing propeller rotation velocity and water pressure on the blades, such rotation further allowing for changes in blade pitch from a fixed low pitch stop, this stop feature being incorporated axially, transversely outward from the blade shaft, along with a cam profile adjacent to said stop feature that allows for a structured increase in blade pitch change as the blade rotates further within said pocket and outwardly against an adjacent cam ramp on the hub, being controlled in structure by the contact movement of this cam profile against a moveable surface in a top section of the housing, said movement being further controlled in tension and limit by a compression spring and cap constraining said top section of the housing, further allowing entire propeller to be securely mounted axially from the housing to the rotating drive shaft of a boat, allowing the propeller to rotate with the drive shaft and incorporating within the lower section of the hub housing, side exit ports for an over hub exhaust system.
 2. The modular, variable pitch marine propeller of claim 1, further comprising a means of biasing the low pitch setting of all blades, such setting affecting all of the blades, causing all blades to remain biased and locked in a low pitch setting until the forces of the hub rotational velocity, centrifugal force and water pressure reach a point forcing all blades simultaneously to move off of the bias point to a higher pitch point, this initial bias setting accomplished by means of a flat surface extending outward, perpendicular to the blade shafts, internally within the encapsulating portion of the blade within the hub housing, said surface resting on an adjacent flat surface of the bottom section of the hub housing adjacent to the blade pockets.
 3. The modular, variable pitch marine propeller of claim 2, wherein the shafts of the blades contain a larger radiused diameter near the end opposite the blade surface that rotates axially with the blade upon an increase in pitch rotation need and is kept within the pocket by a corresponding larger diameter section of the pocket encapsulating the blade shaft.
 4. The modular, variable pitch marine propeller of claim 2, wherein the flat surface extending outward, perpendicular to the blade shaft adjoins a cam profile, said cam profile allowing for a controlled rotation of the blades upon sufficient force as previously described, to overcome the bias force being applied toward a lower pitch setting stop point, such rotation accomplishing a higher pitch setting of the blades, such pitch change made easier by the blade shafts being non centered and biased toward the posterior portion of the blades.
 5. The modular, variable pitch marine propeller of claim 1, wherein the upper section of the hub housing contains a flat surface under spring tension, that contacts the cam profile of all blades and applies spring force on the cam profiles with a natural tendency toward the bias low pitch setting flat stop point, said surface rising axially within the hub housing against an opposing compression spring, thus the more rise the more spring tension, thus along with the cam profile provides a controlled rise in blade pitch.
 6. The modular, variable pitch marine propeller of claim 1, wherein a middle section of the hub housing contains appropriately shaped openings, allowing the cam profiles of the blades to protrude through the bottom portion of the middle hub housing, allowing the bottom flat surface of the upper section of the hub housing to contact the cam profiles of the blades.
 7. The modular, variable pitch marine propeller of claim 6, wherein the upper portion of the middle section of the hub housing contains a hollow, threaded section, said threaded section allowing for a cap to be threaded onto it, securing the top movable section of the hub housing, said securing accomplished by means of a compression spring captured between the cap and a pocket within the upper movable section of the hub housing, the tension of the spring and the amount of threads engaged thus allowing for a set limit to the upward travel of the upper section of the hub housing, thus limiting the extent of high pitch setting on the cam and blade rotation and said hollow threaded section providing a flat surface within the hollow area with splined cuts allowing for the insertion of an off the shelf bronze splined insert that aligns with the splined surfaces of a boat motor shaft.
 8. The modular, variable pitch marine propeller of claim 1, wherein the lower section of the hub housing contains multiple hollow sections anterior to the blade pockets, said section having a cone shape aligned with the hub center axis, said shape decreasing in diameter toward the blade pocket area and exiting outward toward the upper portion of the lower section of the hub housing, thus providing an anterior over hub exhaust exit instead of the usual thru hub exhaust exit, said reduction in diameter allowing for an increase in air volume and decrease in back pressure from the exhaust gases exiting the boat motor.
 9. The modular, variable pitch marine propeller of claim 8, wherein the upper area of the lower section of the hub housing contains multiple half circle pockets, with larger radiused diameter areas closer to the center of the hub housing, where said pockets provide a means of encapsulating all the blade shafts, when assembled to the middle hub housing area these pockets align with similar half circle pockets in the middle section of the hub housing, making for complete circular pockets capturing all the blade shafts, said upper area also having a ramped protrusion off the top flat surface allowing for blade shaft protrusion contact for pitch change, as the blade shaft is forced to extend outward from the hub center and rotate up said ramp upon sufficient prop speed.
 10. The modular, variable pitch marine propeller of claim 1, wherein the lower and middle sections of the hub housing are cylindrical in shape and each section contains half of a circular opposing exterior extrusion, which when the sections are combined as is the intent of this invention, they provide a complete profile circularly that prevents interference between the outside walls of the hub housing and the posterior and anterior ends of all the blades when said blades rotate axially on their shafts for pitch change.
 11. The modular, variable pitch marine propeller of claims 1-10, whereby the two forces acting on the blades of centrifugal force and water pressure are able to act independently from one another non coupled, so that the blade shafts are allowed to travel axially outward from the hub center by centrifugal force and are forced to rotate upon such travel by contact between a ramped surface on the top flat surface of the hub bottom section and the cam profile protrusion protruding outward from the blade shaft, said action being independent of the shaft rotation occurring from increased water pressure behind the blades upon sufficient boat travel speed. 